Trayvon was racially profiled, stalked, chased down, and then physically confronted. Did Martin pull Zimmerman out of his truck? Zimmerman didn't even have to leave his truck. Looks like he (Martin) was standing his ground. He didn't know who Zimmerman was because he didn't look like a police officer (no uniform, badge, police lights on his truck).
I agree with T-Spoon. It just doesn't make sense for a grown armed man yelling for help. It would make more sense to me that an unarmed kid, who was being hunted down was the one screaming for help. If he (Zimmerman) knew help was on the way, why not fight until help arrives? His injuries were insignificant.
You can create doubt in just about every case!
I think the call that Zimmerman placed is doing to be his downfall.
"these a^!holes always get away" tells me that Zimmerman was determined to not let Martin get away and took the law into his own hands.